The Talbot effect in X-rays is made use of in differential phase contrast imaging in order to measure the lateral shifts of interference fringes caused by phase shifts in the X-ray field induced by gradients of the X-ray refractive index. The phase shift depends on energy such that the shift in phase of the X-ray wave at the monochromatic component corresponding to energy E by a small wedge is given by:
      ΔΦ    ⁡          (      E      )        =            ΔΦ      ⁡              (                  E          0                )              ⁢                  E        0            E      where ΔΦ(E0) denotes the phase shift at the monochromatic component corresponding to energy E0. This is in total analogy with the well-known dispersive effect of a prism in the optical band of frequencies which can be used to analyze the spectral content of light. In the visible domain around 5.0·1014 Hz the refraction of light is sufficiently strong (water: n=1.33) to use the angular dispersion directly for singling out a given monochromatic component from a polychromatic spectrum using a single slit. In the X-ray domain the refractive index is much closer to one (and actually smaller than one), e.g. for X-rays with 30 keV of energy (7.25·1018 Hz), the refractive index is 0.9999997, leading to minute diffraction angles and related small dispersion effects.
U.S. Pat. No. 5,812,629 describes an apparatus and a method for radiography practice. The described apparatus operates via Talbot filters using two pre-objected micro-fabricated gratings.
US 2013/0028378 A1 describes a differential phase contrast X-ray imaging system including an X-ray illumination system, a beam splitter arranged in an system arranged in an optical path to detect X-rays after passing through the beam splitter.
WO 2007/125833 A1 describes an X-ray image picking-up device and its method for a continuous X-ray generation for picking up an image with a high sensitivity based on X-ray phase information.
WO 2009/104560 A1 describes an X-ray source enabling the omission of installation of multi-slits in a highly sensitive X-ray imaging method using an X-ray Talbot-Lau interferometer and an X-ray imaging apparatus using the X-ray source.
U.S. Pat. No. 4,578,803 describes an energy-selective X-ray imaging system, wherein images are produced using two scintillating screens separated by an X-ray hardening filter. In the described system, photosensitive surfaces individually receive the light images from each screen. For the case of the described energy-selective X-ray imaging system, the resultant image transparencies are read out optically using a partially reflecting mirror between the transparencies and detecting the reflected and transmitted light. The X-ray spectral separation between the two acquired images can be further increased by using an X-ray source filter of the described energy-selective X-ray imaging system, having a K-absorption edge in the vicinity of the region of overlap of the two spectra.